Introduction to View in SQL
In SQL, a view is a virtual table based on the outcome-set of an statement.
A view contains rows and columns, just like an original table. The entries in a view are entries from one or more original tables in the database.
You can add functions, WHERE, and JOIN statements to a view and display the data as if the data were arriving from one single table.
CREATE VIEW Syntax
CREATE VIEW view_name AS
SELECT column1, column2, …
FROM table_name
WHERE condition;
Note: A view always shows up-to-date data! The database storage recreates the data, using the view’s statement, every time a user queries a view.
SQL CREATE VIEW Examples
Here, creates a view that shows all customers from Brazil:
Example
CREATE VIEW [Brazil Customers] AS
SELECT CustomerName, ContactName
FROM Customers
WHERE Country = 'Brazil';
We can query the view above as follows:
Example
SELECT * FROM [Brazil Customers];
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Here, Creates a view that selects every product in the “Products” table with a price higher than the average price:
Example
CREATE VIEW [Products Above Average Price] AS
SELECT ProductName, Price
FROM Products
WHERE Price > (SELECT AVG(Price) FROM Products);
We can query the view above as follows:
Example
SELECT * FROM [Products Above Average Price];
Here view can be updated with the CREATE OR REPLACE VIEW command.
SQL CREATE OR REPLACE VIEW Syntax:-
CREATE OR REPLACE VIEW view_name AS
SELECT column1, column2, ...
FROM table_name
WHERE condition;
Here SQL adds the "City" column to the "Brazil Customers" view:
Example
CREATE OR REPLACE VIEW [Brazil Customers] AS
SELECT CustomerName, ContactName, City
FROM Customers
WHERE Country = 'Brazil';
Here the view is deleted with the DROP VIEW command.
Syntax
DROP VIEW view_name;
Here SQL drops the "Brazil Customers" view:
Example
DROP VIEW [Brazil Customers];
